System and method for emergency lighting

ABSTRACT

A lighting network (100) and methods therefore are disclosed. The lighting network (100) a plurality of lighting units (10) that can operate on AC power and DC back up power if the AC power is removed. A controller (15) is used to redistribute the DC power between the plurality of lighting units (10) in the event that DC power is low or exhausted in one of the plurality of lighting units (10).

This invention relates to systems and methods for providing state-bylighting and, more particularly, a network based distributed plug-inemergency lamp system.

In many areas around the world, electric power provided by a utilitycompany may be unreliable. In such areas, buildings are typicallyequipped with an emergency lighting system. The emergency lightingsystem generally consists of a single (battery backup) emergency lampthat is usually placed in the living room/hall of the house. Even thoughthe conventional emergency lamp switches ON when a power outage occurs,such conventional emergency lighting systems provide little help if theoccupants the house are not in the single room in which the emergencylamp is located. This also leads to energy waste when the occupants arenot in the room in which the emergency lamp is located.

To illuminate another room, a fully/partially charged battery backuplamp must be used. This either leads to inconvenience or safety hazardin an emergency by having to find/move the battery backup lamp in thedark. To experience hassle free light backup, the user has to havemultiple lamps with sufficient storage/battery life. This solution iscostly.

Accordingly, a need exists in the art for systems and methods to addressthe shortcomings of the conventional emergency lighting systemsdescribed above.

One aspect of the present invention is related to a network baseddistributed plug-in emergency lamp solution that can provide lightbackup in multiple rooms or utility areas of the building. Unlike theconventional emergency lamps discussed above, the plug-in emergency lampaccording to embodiments of the present invention can be used as normallamp, has less storage and/or has intelligence to minimize the wastageof backup energy when the user is not around or when daylight isavailable. The network based distributed plug-in emergency lamps canconnect a battery storage system that can be used by all the plug-inemergency lamps in the building during the power outage. Such a powersharing network helps to extend the light availability for limitedperiod in the occupied places of building. In this way compact low costlamps in different rooms can be combined together to give the userbetter performance.

In another aspect of the present invention, the power sharing networkconnects all the plug-in emergency lamps on existing AC wiring in thebuilding during the power outage interval, identifies the availablestorage in each of the plug-in emergency lamps and adjusts the powerresource by sending power from one plug-in emergency lamp to another toextend the light availability in the occupied spaces of building.

In another embodiment, the power sharing network connects all theplug-in emergency lamps with additional wiring to form a DC network,identifies the available storage in each of the plug-in emergency lampsand adjusts the power resource by sending power from one plug-inemergency lamp to another to extend the light availability in theoccupied spaces of building for a predetermined time.

In another embodiment of the present invention, the proposed inventionuses the additional wiring to exchange the power as well as data betweenthe plug-in emergency lamps during the power outages and uses asimplified the control architecture.

In another embodiment of the present invention, an additional batterybank can be connected to the DC network to extend the light in one ormore of the rooms, in case of the emergency or a planned activity. Thismay be done by reserving one node on DC network and connecting theadditional battery bank to the (vacant) reserved node.

In other embodiments of present invention, various types of conventionalemergency lamps can also be added and networked together with theplug-in emergency lamps.

In another embodiment of the invention, a grid power monitoring unit isused to communicate with all the plug-in emergency lamps to configurethe network.

In one embodiment, the present invention is directed to a lightingnetwork including a plurality of lighting units that can operate on ACpower and DC power if the AC power is removed. A controller is arrangedto redistribute the DC power between the plurality of lighting units.The lighting network also an AC power monitoring unit arranged to detectthe presence or absence of the AC power. In the lighting network thecontroller redistributes the DC power using the same distribution pathused by the AC power.

In another embodiment, the present invention is directed to a lightingunit including a lighting emitting unit, a driver coupled to thelighting emitting unit and an AC/DC converter arranged to supply powerto the driver. A DC battery unit (14) is also coupled to the driver andarranged to supply power to the driver if the AC/DC converter cannotsupply the power to the driver. A controller (15) arranged to requestadditional power if the power from the DC battery unit is running low.The lighting unit also includes a bypass switch that is used to switch,under control from the controller, to the DC power when the AC power isnot available.

In yet another embodiment, the lighting unit further includes a DC inputpath to receive the additional power.

Another embodiment of the present invention is directed to a method forsupplying DC back up lighting for an area. The method includes the stepsof determining if an AC power outage has occurred and determining if thearea was illuminated before the AC power outage occurred. Based upon thedeterminations, if the area was not illuminated the DC back up lightingis not supplied for the area and if the area was illuminated supply theDC back up lighting if the illumination was not daylight.

In a further embodiment of the present invention, an on-off switch of adependable lighting unit is replaced by tactile switch. Whenever a userpresses the tactile switch, power to the dependable lighting unit ismomentarily cut OFF and the event is registered. Whenever, the eventgets registered; the dependable lighting unit toggles from ON to OFFstate or vice versa. If the loss of power is not momentary then theevent is recognized as power outage condition.

In yet another embodiment of the present invention, a control circuit isused to differentiate between the tactile switch operation andmomentarily mains voltage dip to avoid false triggering.

In general, the various aspects and embodiments of the present inventionmay be combined and coupled in any way possible within the scope of theinvention. The subject matter that is regarded as the invention isparticularly pointed out and distinctly claimed in the claims at theconclusion of the specification.

The foregoing and other features and advantages of the invention will beapparent from the following detailed description taken in conjunctionwith the accompanying drawings.

FIG. 1 shows a schematic of the power sharing network for the plug-inemergency lamps (or dependable lamps) according to an embodiment of theinvention.

FIG. 2 shows a schematic of the power sharing network for the plug-inemergency lamps (or dependable lamps) according to another embodiment ofthe invention.

FIG. 3 shows an emergency lamp “snap shoot” method according to anotherembodiment of the present invention.

FIG. 4 shows a schematic of a tactile switch feature for the plug-inemergency lamp according to another embodiment of the invention.

FIG. 5 shows an operational method for a dependable lamp with a tactileswitch.

As shown in FIG. 1, a network 100 of dependable lamps 10 will work in aconventional mode in the presence of AC power supplied by AC mains 11.In the conventional mode, the dependable lamps 10 operate asconventional individual lamps. When the AC power is available, thedependable lamps 10 are in a battery charge or trickle charge mode. Acontrol switch (not shown) may be used to switch the dependable lamp ONor OFF. The presence of the AC power (i.e., grid/main power) ismonitored by a power monitoring unit 12. In absence of the AC power, thepower monitoring unit 12 sends a signal to power isolator switch 13 todisconnect local distribution from the AC mains 11. In absence of the ACpower, all the dependable lamps 10 in the network 100 switch to form DCnetwork for DATA/power transfer. When the AC power is restored, thepower monitoring unit 12 sends another signal to all the dependablelamps 10 to switch to the AC power.

The network 100 is disconnected from the AC mains 11 through the powerisolator switch 13 and each of the dependable lamps 10 is be powered bya charge management/battery unit 14. It is noted that the chargemanagement/battery unit 14 may be two separate components.

In the event that a particular one or more of the dependable lamps 10needs to provide light beyond specified limited period (e.g., some settime or the capacity of the battery 14), a user can trigger theparticular lamp via a remote device or press switch or touch sensor (notshown). The network 100 may also include a proximity sensor 20 and/or adaylight sensor 21 to optimize the power resource to extend the lightavailability. The sensors 20/21 may also be included as part of alighting driver 18. According, instead or in addition to the triggerfrom the user, the dependable lamp 10 can automatically sense the userand turn on and, if needed, obtain additional power as described below.

If the particular lamp 10 has a completely discharged battery 14 thenthe particular lamp 10 will search for power availability on the network100 by sending a power dry up signal to one or more of the otherdependable lamps 10 in the network 100. This is done by a communicationcontroller 15.

The choice of communication may be PLC or any other conventional means.PLC stands for power line communication or power line carrier (PLC),also known as power line digital subscriber line (PDSL), mainscommunication, power line telecom (PLT), power line networking (PLN), orbroadband over power lines (BPL) and are systems for carrying data on aconductor also used for electric power transmission.

The dependable lamps 10 that receive the power dry up signal and whichhave enough stored power in their own batteries 14 will send back asignal to the dependable lamp 10 which originated the power dry upsignal request. Each of the dependable lamps 10 has a uniqueidentifiable code that can be addressed. Once protocol hand shakingbetween the two or more dependable lamps 10 is complete the dependablelamp 10 which has stored energy will allow the access to its battery 14to the dependable lamp 10 which originated the power dry up signalrequest.

To enable the power from the battery 14 to pass from one of thedependable lamps 10 to another on the network 100, AC/DC converters 16on both the dependable lamps 10 are bypassed using bypass switches 17.The bypass switches 17 remain connected for a predetermined time or maybe controlled by the dependable lamp 10 which originated the dry upsignal request (i.e., the sender lamp 10).

Before connecting power to the lighting driver 18 of a lighting unit 19,the communication controller 15 of the sender lamp 10 will ensure thatlight is not being generated the lighting unit 19. The lighting unit 19may be a LED unit or other lighting producing unit. The communicationcontroller 15 will also control the charge management/battery unit 14 soas not to charge the sender lamp 10's battery 14 and to use the powerreceived only to power the lighting unit 19 via the lighting driver 18.The other dependable lamps 10 in the network 100 will be either isolatedor in high impedance mode. In this manner, the network 100 functions ina seamless manner to make the light available to the user for apredetermined time.

Once the AC power is restored, the network 100 will monitor andreconnect the dependable lamps 10 in the network 100 to the AC mains 11.

FIG. 2 shows another embodiment of a power sharing network 200 forplug-in emergency lamps. The same reference numbers are used forelements that are the same or similar to those shown in FIG. 1. As shownin FIG. 2, separate wiring is used to share battery power between thedependable lamps 10 as well as from a master storage unit 22. Theseparate wiring is also used to allow the dependable lamps 10 tocommunicate with each other. When the AC power is available, each of thedependable lamps works independently as a conventional lamp with AC gridpower.

In the event of an AC grid power outage, the dependable lamps 10 cansense the presence of the user in the room and turned ON from the powerassociated with the battery 14. When the battery 14 associated with theindividual dependable lamp 10 is used up the charge management system 14will search for power availability on the DC network by sending thepower dry up signal to each of the other dependable lamps 10 in thenetwork 200. This request and reply procedure is similar to the protocoldescribed in regard to the embodiment shown in FIG. 1. Serial switchesin the charge management unit 14 in the dependable lamps 10 are used toform the low impedance network for power flow from one of dependablelamps 10 to another. The network 200 may also include thepresence/daylight sensors 20/21 to optimize the power resource to extendthe light availability.

In another embodiment, the networks 100 and/or 200 may include “snapshot” feature to memorize a state of the room at the instant of the ACpower outage. The dependable lamps 10 will switch on only when the roomwas in an illuminated state before the AC power outage occurred.Otherwise the dependable lamp 10 will not turn on automatically in theevent of the AC power outage if the room was in non-illuminated state.The daylight sensor 21 is used to sense the illumination condition ofsurroundings at the instant of the AC power outage. The daylight sensor21 should be able to differentiate between day light and artificiallight so that it should not switch on during day.

It should be understood that the “snap shot” feature described hereinmay be used with other types of emergency lamps and is not limited touse with only networked dependable lamps 10.

A method for the snap shot feature to enable switching on/off of thedependable lamps 10 based on room lighting condition is shown in FIG. 3.The method can be embodied as an algorithm or computer readable codethat is accessible or embedded in one of the components (e.g., thecommunication controller 15) of the dependable lamp 10. The component,for example, can be a microcontroller, ASIC or ROM.

In step S1 of FIG. 3, it is determined if the AC power outage hasoccurred. In step S2, it is checked if the room was illuminated at thetime of the AC power outage. In step S3, it is determined if theillumination was day light. In step S4, it is checked if the room iscurrently occupied. In step S5, the dependable lamp 10 is turned on. Instep S6, the dependable lamp 10 is maintained in the off state. In stepS7, it is checked if there is movement in the room. In step S8, thedependable lamp is turned on. In step S9, it is determined if the ACpower as been restored. In step S10, the dependable lamp 10 is turnedoff.

It should be understood by one of ordinary skill in the art that theflow of the method shown in FIG. 3 can be adjusted to cover variouspermutations of turning the dependable lamp 10 on/off based upon thesignals from the presence sensor 20 and the day light sensor 21 as wellas restoration of the AC power.

In another embodiment, the presence sensor 20 should be able todistinguish between the presence and the movement of the user so thatwhenever the presence senor 20 senses the movement in the room, thedependable lamp 10 is switched on even if the snap shot is dark at thetime of the AC power outage. The presence sensor 20 takes control oncethe presence sensor 20 detects the movement in the room and switches offor on the dependable lamp 10 based on the movement detection.

In another embodiment, the dependable lamp 10 may also include anindicator to display various state conditions. For example, theindicator can show the user that the dependable lamp 10 has sensed thedark condition at the time of the AC power outage and kept the lamp inoff condition, e.g., the user may be asleep in the room.

In another embodiment, to extend availability of light in one or more ofthe rooms, one node of the network 200 may be kept vacant intentionally.Whenever a charged battery is connected to the vacant node, the vacantnode will communicate with the master storage unit 22 which will makethe sharing power from the vacant node to the requester dependable lamp10.

In another embodiment, the dependable lamps 10 may have variable lightlevel outputs to reduce/extend the power backup time. Such dimming maybe varied based on a predetermine time or a predetermined batterythreshold level.

In a further embodiment of the present invention, a conventional on-offswitch for controlling the dependable lamps 10 is replaced by a tactileswitch 30. Whenever a user presses the tactile switch 30, power to thedependable lamp 10 momentarily cuts OFF and such event is registered.Whenever the event gets registered; the dependable lamp 10 toggles fromON to OFF state or vice versa. This means if the dependable lamp 10 isON condition it shifts to OFF condition or vice versa. If the dependablelamp 10 determines that a loss of grid power is beyond a predeterminedthreshold limit then the event is recognizes as a power outage conditionand lighting battery backup function is initiated.

FIG. 4 shows a schematic of the dependable lamp 10 including the tactileswitch 30 (normally closed). In this embodiment, the dependable lamp 10includes two full bridge rectifiers (31 and 32), the lamp driver 18, thecharge management unit 14, a lamp state monitoring unit 33 and a mainsvoltage monitoring unit 34. The output of the full bridge rectifier 32is not filtered and is monitored by the mains monitoring unit 33 (e.g.,via a voltage divider). The mains voltage monitoring unit 33 includes amains voltage slope measurement subunit and an outage determinationsubunit (not separately shown in FIG. 4). These subunits can be eitherhardware components or ASIC (Application Specific Integrated Circuit) orembedded software or combinations thereof. As shown by the dashed linesin FIG. 4, the various functional blocks communicate among themselves.It should also be understood that the functional blocks shown in FIG. 4may be embedded in one controller or multiple controllers.

The tactile switch 30 (e.g., normally closed (NC) single pole) is usedto control the dependable lamp 10. Whenever the tactile switch 30 ispressed the mains supply is disrupted and this event is sensed by mainsvoltage monitoring unit 33 through the full bridge rectifier 32. Thisevent is then recorded by the mains voltage monitoring unit 33. If themains supply is not restored within predefined time (e.g., an internaltimer triggered by the event reaches maximum set value, preferably inthe range of 100 milli seconds to 1 second, but other values may beused), the event is determined as a mains outage. If the dependable lamp10 was in the ON condition previous to the occurrence of the event, asecond timer may also triggered. In this case, power for the dependablelamp 10 is supplied from a (battery) backup for a predefined time untilthe second timer reach a predetermined set value (preferably in therange of 10 minutes to 60 minutes but other values can be used). Thesecond timer may be used to control the amount of time the dependablelamp 10 is on the battery backup. If the lamp was in OFF position, theevent can be ignored.

If the mains supply is restored within the predefined time, i.e. thefirst timer has not reached maximum set value, the mains voltagemonitoring unit 33 records this as a second event. In this condition,the mains voltage monitoring unit 33 analyzes a slope of the mainsvoltage (the mains voltage waveform is typically monitored). Based uponthe analysis, it can be determined that the second event is either avoltage dip or intended tactile switch operation. In the event of theintended tactile switch operation, the slope (dv/dt) of mains voltage ishigher than during the voltage dip in the mains voltage. In the case ofthe voltage dip condition, the second event can be ignored. In the caseof the intended tactile switch operation, the dependable lamp 10 stateis changed (toggled) from ON to OFF or vice versa. This will help avoidfalse triggering of the dependable lamp 10.

FIG. 5 shows an operational method for a dependable lamp with a tactileswitch. As shown in FIG. 5, in step S20, the dependable lamp 10 isinitially in STATE1 (i.e., the ON condition). The dependable lamp 10 maybe in either the ON or OFF state initially. In step S21, the dependablelamp 10 checks for the availability of the mains/grids power. If thegrid power is available, the dependable lamp 10 does not take any actionto change state or condition. Otherwise, in step S22, the timer1 isinitiated if the loss of grid power is detected. In step S23, it ischecked if the mains voltage is restored within the predefined time. Ifyes then in step S24, is determined if the event is an intended tactileswitch operation or a voltage dip in the mains voltage. In the case ofthe intended tactile switch operation, in step S25, the dependable lamp10 is switched (toggled) from STATE1 to STATE2 in this example and thetimer1 is reset.

If the mains voltage is not restored within the predefined time, thetime1 is reset (step S25) and it is checked if the dependable lamp 10 isalready in the ON state (step S26). If the dependable lamp 10 is alreadyin the ON state before the power outage then power (step 27) will beprovided through a storage element (e.g., battery). The battery backuptime is controlled by via timer2 (steps S28 and S29).

The foregoing detailed description has set forth a few of the many formsthat the invention can take. The above examples are merely illustrativeof several possible embodiments of various aspects of the presentinvention, wherein equivalent alterations and/or modifications willoccur to others skilled in the art upon reading and understanding of thepresent invention and the annexed drawings. In particular, regard to thevarious functions performed by the above described components (devices,systems, and the like), the terms (including a reference to a “means”)used to describe such components are intended to correspond, unlessotherwise indicated to any component, such as hardware or combinationsthereof, which performs the specified function of the describedcomponent (i.e., that is functionally equivalent), even though notstructurally equivalent to the disclosed structure which performs thefunction in the illustrated implementations of the disclosure.

The principles of the present invention are implemented as anycombination of hardware, firmware and software. Moreover, the softwareis preferably implemented as an application program tangibly embodied ona program storage unit or computer readable storage medium consisting ofparts, or of certain devices and/or a combination of devices. Theapplication program may be uploaded to, and executed by, a machinecomprising any suitable architecture. The computer platform may alsoinclude an operating system and microinstruction code. The variousprocesses and functions described herein may be either part of themicroinstruction code or part of the application program, or anycombination thereof, which may be executed by a CPU, whether or not suchcomputer or processor is explicitly shown. In addition, various otherperipheral units may be connected to the computer platform such as anadditional data storage unit and a printing unit.

Although a particular feature of the present invention may have beenillustrated and/or described with respect to only one of severalimplementations, such feature may be combined with one or more otherfeatures of the other implementations as may be desired and advantageousfor any given or particular application. Furthermore, references tosingular components or items are intended, unless otherwise specified,to encompass two or more such components or items. Also, to the extentthat the terms “including”, “includes”, “having”, “has”, “with”, orvariants thereof are used in the detailed description and/or in theclaims, such terms are intended to be inclusive in a manner similar tothe term “comprising”.

The present invention has been described with reference to the preferredembodiments. However, modifications and alterations will occur to othersupon reading and understanding the preceding detailed description. It isintended that the present invention be construed as including all suchmodifications and alterations. It is only the claims, including allequivalents that are intended to define the scope of the presentinvention.

1-20. (canceled)
 21. A lighting network, comprising: a plurality oflamps comprising: a first lamp comprising: a first direct current (DC)power source configured to provide DC power for the first lamp, and afirst controller configured to cause the DC power to be provided to asecond lamp when AC power is unavailable from the AC power source; andthe second lamp connected to the first lamp, the second lamp comprising:a second DC power source configured to power the first lamp and thesecond lamp based at least on the availability of AC power from the ACpower source and the availability of the DC power at the first DC powersource; one or more sensors arranged to detect a presence of a user, anda second controller, wherein the second controller is configured to senda request signal requesting DC power from the first lamp based on (i) asignal from the one or more sensors provided before the AC power wasunavailable and (ii) a status of the second DC power source.
 22. Thelighting network of claim 21, wherein the one or more sensors of thesecond lamp includes a daylight sensor, and the second controller isfurther configured to bypass requesting the DC power from the first lampwhen illumination by day light is detected by the daylight sensorsubsequent to the AC power being unavailable.
 23. The lighting networkof claim 21, wherein the first lamp and the second lamp each includes abypass switch and an AC/DC converter, and the signal request from thesecond lamp is configured to cause the AC/DC converters to be bypassedvia the bypass switches.
 24. The lighting network of claim 21, whereinthe first lamp is configured to provide a signal request to the secondlamp based on whether the first DC power source has available storedpower for the second lamp.
 25. The lighting network of claim 21, whereinthe first lamp and the second lamp are each configured to record whethera lighting unit of the first lamp or the second lamp, respectively, wason before the AC power was unavailable.
 26. The lighting network ofclaim 21, wherein the first lamp and the second lamp each includes anindicator configured to indicate to a user that a lamp was off at a timewhen an AC power outage occurred.
 27. The lighting network of claim 21,wherein the second controller is configured to bypass providing therequest for the DC power from the first lamp when the one or moresensors indicate a room was unoccupied before the AC power wasunavailable.
 28. A lighting network, comprising: a plurality of lampscomprising: a first lamp that includes: a sensor configured to determinewhether a person is located within a room of the first lamp, and a firstDC power source configured to provide power to one or more lamps of theplurality of lamps when AC power is unavailable from the AC powersource, and a second lamp that includes: a second DC power source, andone or more controllers in communication with the first lamp, whereinthe first lamp is configured to provide a request signal for DC powerwhen: (i) AC power is unavailable to the plurality of lamps, (ii)sufficient power is unavailable from the first DC power source, and(iii) the sensor of the first lamp detected that the room was occupiedbefore the AC power became unavailable, and wherein the second lamp isconfigured to provide the DC power from the second DC power source tothe first lamp in response to the first lamp providing the requestsignal.
 29. The lighting network of claim 28, wherein the first lampincludes a daylight sensor, and the first lamp is further configured toprovide the request for DC power when the daylight sensor of the firstlamp indicates that the room was illuminated by natural light before theAC power became unavailable.
 30. The lighting network of claim 28,further comprising: an indicator configured to indicate that a lamp ofthe plurality of lamps was off at a time when the AC power becameunavailable.
 31. The lighting network of claim 28, wherein each lamp ofthe plurality of lamps is configured to initialize a timer in responseto detecting unavailability of AC power, wherein each lamp is furtherconfigured to determine whether an AC power outage occurred based on avalue of the timer.